Purification of crude synthetic camphor



UNITED STATES PATENT OFFICE.

comes 1!. IESSIIBR, 03 WEST ORANGE, NEW JERSEY, ASSIGNOB TO B. I. no PORT nl M01138 6: COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION 01' nrmewsnn.

PURIFICATION OF CRUDE SYNTHETIC GAMPHOR.

Io Drawing.

To all 'wkomitmay concem:

Be it known that I Jonamms M. Knssma, a citizen of the United. States, and a resident of West Or in the county of Essex and State of our Jerse have invented a certain new and useful urification of Crude Synthetic Cemphor, of which the following is a specification.

This invention relates to the purification of synthetic camphor, and especially of cumphor contaminated with organic halide, and comprises heating the impure camphor with big boiling point-organic-acid salts soluble in molten camphor.

In the manufacture of synthetic camphor from turpentine, the formation of inene hydrohalid such as Einene hydroc lorid, is usually one of the rst operations to be carried out. Although it is relatively easy to convert this latter substance into camphcue and from there into borneol and nally into csmphor small amounts of organic halide such for example as colopbene chlori etc. are tenaciously retained throughout the di erent stages of the manufacture and their removal from the final product was found impossible in some cases or could only be accomplished with considerable difficult by expensive urification processes. uite often the k of proper refining methods was the main reason why synthetic camphor contaminated with traces of organic chloride, but otherwise showing the some valuable pro erties as the natural product, could not e employed for most commercial purposes. The amount of or is chloride present in the synthetic camp or may have been less than 1% and still such a product was liable to gradually split of! free hydrochloric acid and so cause serious trouble whenev er employed. Particularly serious and ob ectIonable was the behavior of such synthetic camphor when it occurred in nitrocellulose plastics such as celluloid, plyralin etc which consist of approximatel 0 nitrocellulose and 30 0 cam hor. isco oration of the more elicat y colored compounds, instability and consequent decomposition of the nitrocellulose were likely to be caused by the s litt'm ,oil' of the hydrochlor c ac d.

The c liief ifliculty which is ordinarily encountered in the refining of s theuc camphor by d distillation, is the evelopmeat of free ydroehlonc cold and only,

Specification of Lott t n Patented Dec. 2'7, 1921.

Application flied February 85, mo. Serial No. 381,858.

yellow colored acid reacting liquid which condenses on the sides of the chamber into which the camlphor vapor is led, and by dropping into 1; e main portion of the properly refined product contaminates it. The presence of hydrochloric acid is not only very Ob ectiOnabIe on account of its destructn e action on the metal lined camphor suhlnmnghchambers, but is apt to cause very serious at er damages by starting discoloration, instability, and consequent decomposition of the nitrocellulose when the latter is made into plastics with camphor containing it.

In my application, Serial No. 351,936 filed January 16, 1920, for process of purifying crude synthetic camphor, I have described a process whereby a. satisfactory product, free from chlorin, can be obtained, this process comprising baking the crude camphor at a temperature above 190 C. until the organic chloride are decomposed. The time inquired, 20 to 30 hours, to complete this reaction is, however, unusually long, and attempts were made to shorten the process as much as possible. The most probable solution of this problem appeared to lie in the addition of a reagent.

It was found by experience that rea cuts were to be aroided which, like a phanapthyl-amin, imparted an objectionable color to the camphor distillate; and further, that, as a rule, those reagents were unsuitable which were insoluble in molten camphor such reagents tending to form a hard and diflicultly removable moss in the bottom of the retort. 7

one class of substances which, I discovered, give very satisfactory results are the salts of the higher fatty acids and esupecially the salts of these acids with an a line earth metal, zinc, lead, or other relatively heavy metal, which are readily soluble in molten com )llOl. Such salts appear to accelerate the ccompositiou ,of the organic chloride and to bind the chlorin or the chlorin derivative which results from this decomposition. Furthermore such salts do not cake in the bottom of the retort and can he removed therefrom without difliculty wlhend distillation of the camphor is comete a p In eneral I have found that the salt emplo should he soluble in molten camphor an that the organic acid which 1s termed from the salt hydrolysis should be substeutially non-volatile under the conditions under which the comphor is to be distilled, these conditions, ordinarily, being utmos- )heric pressure and a. temperature of about ..05 C. It is, furthermore, desirable that the metal radical'o'f said salt be capable of combining with the halo cn in the cumnhor to form a. metal halid w 'ch is insoluble in molten camphor, thereby lessening the denfier of secondary reactions between the motel elid and the complex terpene compomlds present.

The salts which I have found articular-l3 satisfactory, due both to their 15?; cost, cs compared with the higher fatty acid salts above mentioned, and to their eiiioccious halogen-binding action, are the metal resinetes. These resinates are completely soluble in molten camphor, and the resinic (or ebietic) acid from which they are derived does not vaporize appreciable at the tomperature at which the comphor is distilled.

For the metal radical of the organic acid salt, I have found that lead is, in general, preferable to calcium and Zinc. Fused lend resinute, especially prepared from a. high boiling rosin and rod lead or lithorge, and heated especially hi h during preparation so that the final r0 not would not give of. during the distil etion of the cumphor any low boiling substances, gives exceptionally good results.

The baking temperature employed should preferably be above 190 0., n tempers-tore range of from 225 to 240 C. being advantageous.

The following date are typical of the results obtained with purifiers oi the kind de scribed above. Baking of the dry crude synthetic camphor containing from 0.5 to 0.6% chlorin in on iron retort with 3% fused lead resinate and distilling the renctiou product gave results as follows:

3 hrs. at 190 C. (no pressure) left 50% chlorin in the refined roduct; 3 hrs. at 205 C. (slight pressure left 130% chlorin in the rofined'product; and 3 hrs. at 9.30-- 240 C. (20-30 lbs. pressure) left 130% chlo'rin in the refined product.

Of the, salts other than the resinate's, there can be used to advantage the psiruitetes, steal-ates, and oleates of the above mentioned metals, and particularly of lead. Linoleetes acted similarly but imparted a. disagreeable odor to the refined cemphor.

As an example of cerryim out my invention, crude synthetic camp 101 dried is mixed with 3% of fused lead resincte and heated in a. retort for 3 hours up to 230-240 C. After decreasing the temperature in the retort to 210 and reducing slowly the pressure in the retort by opening a valve leedin to an air condenser for a. few seconds, t e cemphor is distilled and thoroughly condensed in large chambers in the usual manner.

Purified synthetic ccmphor can also be obtuined from the properly baked crude product according to methods other than distillation. For example, the baked synthetic comphor may be dissolved in an orgenie solvent such as ethyl alcohol, naphtha, etc. and crystallized from a. hot saturated solution on cooling or from an unsaturated solution on concentration b distillation. An dirt or insoluble material present in en 1 a solution can be removed by filtration through cloth or other filtering mediums.

Although my "invention has been illusso trsted in detail in the above description, it will be understood that the invention is not restricted to the examples or to the particular temperatures and pressures above 'set forth. but that many changes can be made therein without departing from the spirit of the invention. Thus, I have mentioned specificelly tbeuse of temperatures up to 240 C. and pressures of 20 to 30 pounds, these pressures being such as can be safely used in retorts of ordinary boiler steel plate construction. but my invention includes carrying out the baking operation at higher temperatures and higher pressures up to the oint at which the camphor itself begins to decompose. V

The function of compiler-soluble organic acid salts as chlorin removers has been emphasized in the above description because of the primary importance oi eliminating substances capable of giving rise to free hydrochloric acid. It has been observed, however, that the action of these organic acids is beneficial also in the removal of other impurities, such as nitrogen derivetivcs. which exist in the cemphor.

I claim:

1. The process of purifyingcamphor con tsiningz an organic hulid which comprises heating such cemphor in the presence of a high boiling point orzanic acid srlt soluble in molten cemphor rind at a temperature suliicient to brim: about decomposition of the organic halid but below that at which camphor itselfbogins to decompose.

2. Thenrocess of purifying cemphor conmining an orr'enic helid which comprises heating such camnhcr in the presence of a high boiling point organic acid salt soluble in molten cumphor and a temperature of 12.1 from about 190 to 2&0" C.

3. 'The process of separating organic chloride from impure csmphor containing scid chlorid which comprises heating said impure cemphor at 9. temperature of from about 190to 240 C. in the presence of a lead salt of a higher aliphatic acid.

4. The process of separating organic chloride from impure camphor containing said chloride which comprises heating said 180 impure camphor at a. temperature of from about 190 to 240 C. and at a pressure substantially above atmospheric pressure in the preCslsence of a lead salt of a higher aliphatic aci 5. The process of separating organic chloride from impure camphor containin said chloride which comprises heatin sai impure camp'hor at a temperature of from about 190 to 240 0. in the presence of a resinate of a metal.

6. The process of separating organic chloride from impure camphor containing said chloride which comprises heating sa-ic impure camphor at a temperature of from about 190 to 240 C. in the presence of lead resinate.

7. The process of separating organic chlorids from impure ca-mphor containing said chloride which comprises heating said impure camphor at a temperature of from about 190 to 240 C. in the presence of about 8% of lead resinate.

8. The process of separating organic chloride from im ure camphor containing said chlorids whic comprises heating said impure camphor at a tem erature of from about 230 to 240 C. in t e presence of an aliphatic acid salt soluble in molten camphor.

9. The process of separating organic chloride from impure cnmphor containing said chloride which comprises heating said impure camphor at a temperature of from about 230 to 240 C. in the presence of lead resinate.

10. The process of separating organic chloride from impure camphor coptammg said chlorids which comprises heating said impure camphor at a temperature of from about 230 to 240 C. in the presence of a lead salt of a higher aliphatic acid for about 3 hours, and then distilling the camphor.

11. The process of separating or his chloride from impure camphor containing said chlorids which comprises heatin said impure camphor at a temperature of from about 230 to 240 C. in the presence of a lead salt of a higher aliphatic acid for about 3 hours, then reducing the tem erature to about 210 0., and distilling s camphor under atmospheric pressure.

12. The process of separating organic chloricis from impure cam phor contammg said cholrids which comprises heatin said impure camphor at a temperature 0 from about 230 to 240 C. in the presence of about 3% of lead resinate for about 8 hours, and distillin the camphor.

13. T e process of se crating organic chlorids from thorou hl ried impure camphor containing said 0 orids which comprises heating said impure camphor at a temperature of from about 190 to 240 C; in the presence of a higher aliphatic acid salt solu la in molten cam her.

14. The process 0 so crating organic chloride from thorou b1 ed im ure camphor containing sai c orids w ich comprises heating said impure camphor at a tem erature of from about 230 to M0" C. in e presence of about 8% of a lead salt of a higher aliphatic acid for about 8 hours, and separating t e pure camphor from other sub stances present by distillation under atmosphenc pressure.

15. The process of purifyin 'camphor contraining an organic halid w ich comprises heatlngl such camphor in the presence of a salt, so uble in molten camphor, of an oramc acid which is substantially non-volatile at 205 C. under atmos henc pressure, the heating of said camphor being carried on at a temperature suflicient to bring about decomposition of the organic halid but below that at which camphor itself begins to decompose.

16. The process of urifyin camphor contaming an organic xalid w 'ch comprises heating such camphor in the presence of a salt, soluble in molten camphor, of an orgcnlc acid which is substantially non-volatile at 205 C. under atmospheric pressure, the heating of said camphor being carried on at a temperature of from about 225 to 240 C.

17. The process of purifying camphor containing an organic alid which comprises heating such cemphor for about 3 hours in a closed chamber in the presence of a salt,

soluble in molten camphor, of an organic.

acid which is substantially non-volatile at 205 C. under atmospheric pressure, the heating of said camphor being carried on at a tem erature of from about 225 to 240 C.

18. he process of separating organic chlorids from impure camphor containin said chloride which comprises heating sai camphor at a temperature of from about 225 to 240 C. in the presence of a higher fatty acid salt of a. metal capable of combining with chlond to form a metal chlorid insoluble in molten cam her.

19. The process 0 separating organic chloride from im ure camphor contamin said chlorids whic comprises heating said camphor at a temperature of from about 225 to 240 'C. in the presence of a resinatc of a. metal capable of combining with chlorin to form a metal chlorid insoluble in molten camphor.

In testimon whereof I ailixfig si J HANNES M. SS

ature. 

